An osteotomy is a surgical procedure in which a bone is divided or a piece of bone is excised. Typically, the procedure is performed to correct a deformity. For example, the procedure may be performed on a femur and/or tibia to correct deformities such as misalignments in the legs that lead to bow legs (outward bowing of the legs) and knock knees (inward bowing of the legs).
In a perfectly aligned leg, a line running through the center of the hip joint to the center of the ankle joint passes through the center of the knee joint. This is called the weight bearing axis of the knee. In people with improperly aligned legs, the weight bearing axis does not pass through the center of the knee, which may result in abnormal wear of the knee joint, thereby causing pain and leading to failure of the knee.
One of the solutions for this condition is to reshape the bones within the leg using an osteotomy procedure. The goal of the procedure is to realign the leg such that the weight bearing axis runs through the center of the knee. During the procedure, a wedge of bone is cut from a leg bone (e.g., the tibia and/or the femur). The wedge is formed by making a first cut into the bone at a first angle and a second cut into the bone at a second angle. After cutting, the wedge is removed and the remaining bone along the first and second cuts is brought together to reshape the bone, thereby realigning the leg. Finally, the bone is fixed with wires and/or screws and allowed to mend.
The determination of the location and angle of the first and second cuts is based largely on subjective analysis by the surgeon and, thus, is prone to error. Ideally, the first and second cuts will meet precisely at their maximum depth and the second cut will form an angle (i.e., a resection angle) with respect to the first cut that provides the proper amount of correction to the alignment of the leg when the wedge is removed and the cut surfaces are brought together. However, since there is a subjective component to the determination of the cuts, the cut surfaces may not meet precisely. If the cut surfaces do not meet precisely, gaps may be present when the bone is brought together at the cut surfaces, which can hinder mending. In addition, an incorrect resection angle will result in improper correction of the alignment of the leg.
Therefore, there is a need for methods of removing a wedge from a bone such that cut surfaces meet precisely and resection angles are accurately determined. The present invention fulfills this need among others.